1. Field of the Invention
The present invention generally relates to terminals and online systems, and more particularly relates to terminals and an online system which carry out online processing by using data and programs stored in an erasable memory media like a flash memory.
In recent years, the EEPROM, which is a type of erasable ROMs, has seen significant advances in its degree of circuit integration. Now, EEPROMs having as large a memory volume as conventional ROMs are commercially available, known as flash memories.
Flash memories are electrically erasable and capable of rewrite, so that an application of flash memories ranges in a wide variety of fields. Among them, the field of online systems like a totalizator system is expected to be a promising application area, where flash memories can be used as a memory storage of control programs in terminals.
2. Description of the Prior Art
FIG. 1 shows an exemplary block diagram of a totalizator system of the prior art. In FIG. 1, a terminal of the prior art comprises a ROM 201 for storing programs for an initialization process and an EPROM 202 with a large memory volume. The terminal further comprises a communication control unit 203 for controlling communications with a host computer. The communication control unit 203, the ROM 201, the EPROM 202, and the CPU 204 are connected together via a bus.
The CPU 204 carries out the initialization process upon the switching on of the power. Then, the CPU 204 executes programs for online processing to have a data communication with the host computer by controlling the communication control unit 203 in accordance with instructions given by a user through an I/O (Input/Output) device. In FIG. 1, the I/O device, its control unit, etc., are all omitted.
As is well known, in order to rewrite contents of EPROMs, a ROM writer or a similar special device is needed.
Accordingly, when rewriting programs for online processing in a terminal, a board on which an EPROM is mounted should be removed from the terminal to be shipped to the manufacturer's factory. Then, the EPROM is disconnected from the board so that new programs can be rewritten with a ROM writer, and, then, is mounted again on the board.
In other words, the updating and the version tracking of data and programs of online terminals are all carried out by maintenance workers of the manufacturers.
Thus, version information about data and programs is provided on the board, for example, by a seal or a stamp, and maintenance workers carry out each maintenance on the basis of the information provided. Even in the cases that version information is contained in the memory with data and programs, its role is no more than that of a seal or a stamp, and is not involved in sophisticated data processing.
The updating process of data and programs described above is not a simple task. Since many terminals are connected to an online system, many work steps and a great amount of time are required for the updating process. This means a significant amount of work load on the maintenance workers.
If EEPROMs, whose memory contents can be electrically rewritten, are used in terminals, it is possible to rewrite data and programs from a remote host computer, thereby reducing the work load on the maintenance workers.
The lack of enough memory volume in EEPROMs of the prior art requires the use of a number of EEPROMs, which leads to an increase in the size of the terminals. Thus, EEPROMs of the prior art are not used in such fields as totalizator systems which demand a miniaturization of terminals.
The recent technological development of flash memories described earlier, however, makes it possible to replace EPROMs with flash memories without increasing the size of terminals. This means that programs for online processing can now be downloaded from a host computer.
However, the downloading of data and programs from a host computer, if carried out in a straightforward way, may create a new problem.
For example, if a process of downloading is terminated due to a power failure or a software malfunction, a process of rewriting flash memories is also terminated. In this case, a terminal, starting up after the recovery, ends up executing incorrect programs which have been only stored in part.
In order to prevent this, such online systems as mobile telephone systems keep old data and programs of the previous version as an insurance, and use new data and programs only after checking their completeness.
Keeping old data and programs, however, requires a huge amount of memory volume. Thus, it is difficult to employ the method in the fields which demand a miniaturization of terminals.
Accordingly, there is a need in the field of online systems for terminals and an online system which can check the completeness of new data and program downloaded from the host computer and can take a counter measure if necessary.